Synthetic crystalline metal silicate compositions and preparation thereof

ABSTRACT

Crystalline metal silicate compositions are prepared from a silica containing mixture which is substantially free of aluminum ions and which contains a chelating agent by digesting a reaction mixture comprising, a tetraalkylammonium compound, sodium hydroxide, a metal compound, an oxide of silicon, a chelating agent and water, with the reaction mixture containing less than about 100 ppm aluminum. Crystalline borosilicate compositions are of special interest. A method for activating the new crystalline compositions to enhance their usefulness for certain conversion processes is also disclosed.

BACKGROUND OF THE INVENTION

The present invention relates to new crystalline borosilicatecompositions. Further, this invention relates to methods for producingthese new crystalline borosilicate compositions and to a method foractivating them to enhance their usefulness for certain catalyticconversion processes.

Zeolitic materials, both natural and synthetic, are known to havecatalytic capability for various types of reactions, especiallyhydrocarbon conversions. The well-known crystalline aluminosilicatezeolites are commonly referred to as "molecular sieves" and arecharacterized by their highly ordered crystalline structure anduniformly dimensioned pores, and are distinguishable from each other onthe basis of composition, crystal structure, adsorption properties andthe like. The term "molecular sieves" is derived from the ability of thezeolite materials to selectively adsorb molecules on the basis of theirsize and form.

The processes for producing such crystalline synthetic zeolites are wellknown in the art. A family of crystalline aluminosilicate zeolites,designated ZSM-5, is disclosed in U.S. Pat. No. 3,702,886, said patentbeing herein incorporated by reference.

U.S. Pat. No. 3,941,871 relates to novel crystalline metalorganosilicates which are essentially free of Group IIIA metals, i.e.,aluminum and/or gallium. This patent is herein incorporated by byreference. It is noted therein that the amount of alumina present in theknown zeolites appears directly related to the acidity characteristicsof the resultant product and that a low alumina content has beenrecognized as being advantageous in attaining a low degree of aciditywhich in many catalytic reactions is translated into low coke makingproperties and low aging rates. A typical procedure for making theorganosilicates is to react a mixture containing a tetraaklylammoniumcompound, sodium hydroxide, an oxide of a metal other than a metal ofGroup IIIA, an oxide of silicon, and water until crystals of said metalorganosilicates are formed. It is also noted in the patent that thefamily of crystalline metal organosilicates have a definite X-raydiffraction pattern which is similar to that for the ZSM-5 zeolites.Minor amounts of alumina are contemplated in the patent and areattributable primarily to the presence of aluminum impurities in thereactants and/or equipment employed.

U.S. Pat. No. 3,884,835 discloses crystalline silica compositions. Thecrystalline silica materials may also contain a metal promoter which maybe selected from Group IIIA, Group V B or Group VI B elements. Boron isdisclosed as one of the metal promoters.

U.S. Pat. No. 4,088,605 is directed to the synthesis of a zeolite, suchas ZSM-5, which contains an outer shell free from aluminum. The patentstates at column 10, the paragraph beginning at line 20, that to producethe outer aluminum-free shell it is also essential that the reactivealuminum be removed from the reaction mixture. It is thereforenecessary, as noted therein, to process the zeolite and to replace thecrystallization medium with an aluminum-free mixture to obtaincrystalization of SiO₂ on the surface of the zeolite which can beaccomplished by a total replacement of the reaction mixture or bycomplexing from the original reaction mixture any remaining aluminum ionwith reagents such as gluconic acid or ethylene diamine tetraacetic acid(EDTA).

Crystalline borosilicate compositions are disclosed in U.S. patentapplication Ser. Nos. 733,267 and 836,403. These applications relatespecifically to borosilicates and are prepared using the usualprocedures for making the aluminosilicate zeolites. It is noted thereinon page 12 of Ser. No. 836,403 that in instances where a deliberateeffort is made to eliminate aluminum from the borosilicate crystalstructure because of its adverse influence on particular conversionprocesses, the molar ratios of SiO₂ /Al₂ O₃ can easily exceed 2000-3000and that this ratio is generally only limited by the availability ofaluminum-free raw materials.

While the art has provided zeolite catalysts having a wide variety ofcatalytic and adsorbtive properties, the need still exists forcrystalline materials having different and/or enhanced catalyticproperties. For example, an important use for a crystalline material isin conversion processes of oxygenated compounds such as the conversionof dimethyl ether to aliphatic compounds with a minimum amount ofaromatics being formed. Additionally, many hydrocarbon conversionprocesses are performed employing zeolites, i.e., alkylation andisomerization. As is well-known in the art, it is important to maximizeselectivity to the desired product and, as will be shown hereinbelow,the reaction of oxygenated compounds, e.g., dimethyl ether, andhydrocarbons, using compositions prepared by the method of the inventionunexpectedly produce high selectivity to aliphatics and high activitywhich is contrary to that expected from a crystalline zeolite typecomposition containing a low level of alumina.

SUMMARY OF THE INVENTION

A new class of crystalline borosilicate compositions has beendiscovered. These crystalline compositions may be prepared by a specialprocess which requires that the amount of aluminum be carefullycontrolled in the reaction mixture and that a chelating agent beemployed in the reaction mixture. It is noted that when the aluminumcontent of the reaction mixture is below about 100 ppm that the aluminumcontent of the catalyst is about the same with or without the use of thechelating agent. Of special interest is a borosilicate compositionidentified as USI-10B but other specially prepared silica compositionsare included herein; e.g., crystalline silica compositions containingsilica with or without a metal oxide, other than aluminum oxide, e.g.,selected from Group IIIA, Group VB and Group VI B may be speciallyprepared using the method of this invention. While boron is not a metalper se, its oxide is considered a metal oxide as defined herein.

In accordance with the present invention, there is provided crystallinemetal silicates which are substantially free of aluminum, less thanabout 100 wppm (weight parts per million), and which can be identifiedin terms of mole ratios of oxides, as follows: 0.8±0.4 M₂ /_(n) O:W₂ O₃:5 to 500 SiO₂ :0 to 100 or more H₂ O where M is a cation, n is thevalence of said cation, and W₂ O₃ a metal oxide. In a preferred form, Wis boron and M is selected from the group consisting of alkali metalcations, especially sodium, tetraalkylammonium and phosphonium cations,the alkyl groups of which preferably contain 1-6, more preferably, 2-5carbon atoms, and mixtures thereof.

Members of the family of crystalline borosilicate compositions USI-10Bpossess a definite crystalline structure whose x-ray diffaction patternshows the following significant lines, the material being in the driedform:

                  TABLE 1                                                         ______________________________________                                        Interplanar Spacing d(A)                                                                         Relative Intensity                                         ______________________________________                                        11.0               M                                                          9.93               W                                                          9.60               VW                                                         8.89               VW                                                         7.37               VW                                                         7.02               VW                                                         6.65               VW                                                         6.20               VW                                                         6.00               VW                                                         5.94               VW                                                         5.68               VW                                                         5.53               VW                                                         5.34               VW                                                         5.09               VW                                                         4.98               VW                                                         4.57               VW                                                         4.41               VW                                                         4.33               VW                                                         4.23               VW                                                         4.06               VW                                                         3.98               VW                                                         3.81               VS                                                         3.74               M                                                          3.69               MS                                                         3.45               VW                                                         3.41               VW                                                         3.31               VW                                                         3.29               VW                                                         3.23               VW                                                         3.15               VW                                                         3.12               VW                                                         3.04               W                                                          2.97               W                                                          2.93               VW                                                         2.85               VW                                                         2.77               VW                                                         2.71               VW                                                         2.59               VW                                                         2.57               VW                                                         2.49               VW                                                         2.47               VW                                                         2.40               VW                                                         2.38               VW                                                         2.11               VW                                                         2.07               VW                                                         2.00               VW                                                         1.98               W                                                          1.94               W                                                          1.90               VW                                                         1.86               VW                                                         1.82               VW                                                         1.75               VW                                                         1.71               VW                                                         1.65               VW                                                         ______________________________________                                    

These values were determined by standard techniques. The radiation wasthe K-alpha doublet of copper, and a scintillation counter spectrometerwith a strip chart pen recorder was used. The peak heights, I, and thepositions as a function of 2 times theta, where theta is the Braggangle, were read from the spectrometer chart. From these, the relativeintensities 100 I/I_(o) where I_(o) is the intensity of the strongestline or peak, and d(obs.), the interplanar spacing in A. correspondingto the recorded lines, were calculated. In Table 1 the relativeintensities are given in terms of the symbols VW=very weak (less than10), K=weak (10-19), M=medium (20-39), MS=medium strong (40-70) andVS=very strong (greater than 70). Ion exchange of the cation M withother cations reveals substantially the same pattern with some minorshifts in interplanar spacing and variation in relative intensity. Otherminor variations can occur depending on the metal (W) to silicon ratioof the particular sample and on whether it had been subjected to thermaltreatment.

The borosilicates of the invention can be suitably prepared e.g., in anautoclave, by preparing a reaction mixture which is substantially freeof aluminum ions, less than about 100 wppm, based on the weight ofsilica in the reaction mixture, and which contains tetrapropyl ammoniumion, e.g., from the bromide or hydroxide, sodium hydroxide, a boroncompound, an oxide of silicon, a chelating agent, e.g., EDTA, and waterand having a composition, in terms of mole ratios falling within thefollowing ranges:

    ______________________________________                                                        Broad    Preferred                                            ______________________________________                                        OH.sup.- /SiO.sub.2                                                                             .05-3      0.20-0.90                                        R.sub.4 N.sup.+ /(R.sub.4 N.sup.+ + Na.sup.+)                                                   0.1-1      0.20-0.8                                         H.sub.2 O/OH.sup.-                                                                              10-500     60-120                                           SiO.sub.2 /W.sub.2 O.sub.3                                                                      5-500      12-50                                            SiO.sub.2 /EDTA   1-1000     20-100                                           ______________________________________                                    

wherein R is propyl and W is boron and maintaining the mixture untilcrystals of the borosilicates are formed. It is noted than an excess oftetrapropylammonium hydroxide can be used which would raise the value ofOH⁻ /SiO₂ above the ranges set forth above. The excess hydroxide, ofcourse, does not participate in the reaction. Alternate methods ofpreparation, such as by refluxing with sodium chloride and sulfuric acidas shown hereinbelow in Example 2, may result in the OH⁻ /SiO₂ and R₄ N⁺/(R₄ N⁺ +Na⁺) ratios falling outside the above ranges. Thereafter thecrystals are separated from the liquid and recovered. Typical reactionconditions consist of heating the foregoing reaction mixture at anelevated temperature, e.g., about 50° to 250° C., or higher, for aperiod of time of from about six hours to 60 days. A preferredtemperature range is from about 100° C. to 190° C., with the amount oftime at a temperature in such range being from about 1 to 16 days.Reflux, an autoclave or other reaction method may be employed.

The digestion of the gel particles is carried out until crystals form.The solid product is separated from the reaction medium, as by coolingthe whole to room temperature, filtering, and water washing.

The foregoing product is dried, e.g., at 110° C. for from about 8 to 24hours or longer. Of course, milder conditions may be employed ifdesired, e.g., room temperature under vacuum.

An important feature of the invention is a process for activating thenovel crystalline compositions of the invention for enhanced use invarious conversion processes. In general, the activation procedurecomprises:

(a) Heat treating the dried silicate composition at e.g., about200°-900° C., preferably about 400°-600° C. for about 1 to 60 hours,preferably 10-20 hours;

(b) Treating the heated silicate with a reducing agent for about 1 to 80hours, preferably 2 to 48 hours at about 200°-900° C., preferably 400°to 600° C.; and

(c) Heat treating the reduced silicate using the procedure of step (a).

In a preferred embodiment, the activation procedure comprises:

(1) Heat treating the dried silicate composition at e.g., about200°-900° C., preferably about 400° to 600° C. for about 1 to 60 hours,preferably 10 to 20 hours;

(2) Ion exchanging the heat treated silicate with a material which uponfurther heat treating decomposes to provide silicate having a hydrogencation;

(3) Washing and drying the exchanged silicate;

(4) Heat treating the dried silicate using the procedure of step (1);

(5) Treating the heated silicate with a reducing agent for about 1 to 80hours, preferably 2 to 48 hours at about 200°-900° C., preferably 400°to 600° C.; and

(6) Heat treating the reduced silicate using the procedure of step (1).

It will be appreciated by those skilled in the art that steps (1)-(4),inclusive of the preferred embodiment, and step (a), above, arewell-known and represent a method commonly used to activate zeolite typecatalysts. The composition of the invention may also be suitablyemployed in the form obtained after step 4 or after step a. Steps b andc and 5 and 6 represent the method of further activating the compositionand is hereinafter termed "Redox Treatment". Heat treating may be donein any atmosphere as is known in the art and is preferably done in air.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As noted hereinabove, and as known in the art, the procedure forpreparing zeolites, e.g., aluminosilicates, is well-known. It is anessential feature of the present invention however, that the crystallinecomposition be prepared using a reaction mixture containing, based onweight percent silica, less than about 100 wppm aluminum ions,preferably less than about 50 wppm and a chelating agent, such asethylene diamine tetraacetic acid (EDTA), nitriliotriacetic acid (NTA)and 8-hydroxyquinoline in an amount of about 0.005 to 5 parts chelatingagent, preferably 0.05 to 0.25 parts. Aside from other differences withprior art crystalline silica compositions, the borosilicate compositionsformed herein are substantially free of aluminum with the molar ratio ofSiO₂ /Al₂ O₃ being greater than about 8,000, and even 30,000. Thefollowing chelating agents used to prepare borosilicates providedcompositions which could not be activated using the Redox Treatment ofthe invention: pyridine-2-carboxylic acid, 8-hydroxyquinoline-5-sulfonicacid and sodium glucoheptonate (Seqlene 540).

It is not known why the crystalline compositions of this inventionprovide such unexpected properties as high dimethyl ether reactivitywith concomitant aliphatic hydrocarbon selectively, and lack ofconversion of ethylene and methanol. As will be shown hereinbelow,crystalline compositions not prepared using both a low aluminum leveland chelating agent do not have these properties and, cannot be RedoxTreated to provide a crystalline composition having enhanced catalytichydrocarbon or oxygenated compound conversion properties, among others.It is possible to theorize that a low aluminum levels the chelatebecomes entrapped as the [--O--Si--O--B--O--]_(n) chains crystallize toform the three dimensional crystal network. Subsequent thermal treatmentmay create cavities which have an internal surface modified by thechelate.

In preparing the crystalline compositions of the invention it isimportant that substantially aluminum-free raw materials be employed.The substantially aluminum free silica source can be any of thosecommonly considered for use in synthesizing zeolites such as powderedsolid silica, silicic acid, colloidal silica or dissolved silica. Apreferred silica source is Cab-O-Sil, sold by Cabot Co.

The substantially aluminum free metallic oxide material may be selectedfrom the group consisting of Group III A, Group V B and Group VI B. Apreferred metal is boron and the source may be boric oxide, boric acid,sodium borate, among others.

The specific crystalline compositions described, when prepared in thepresence of organic cations, are inactive, possibly because theintracrystalline free space is occupied by organic cations from theforming solution. They may, however, be activated by heat treatmentusing known techniques such as heating in an inert atmosphere or air at200°-900° C., for 1 to 60 hours. This may be followed by ion exchangewith ammonium salts and further heat treatment at 200°-900° C. ifdesired.

The crystalline compositions can be used either in the alkali metalform, e.g., the sodium form, the ammonium form, the hydrogen form, orother univalent or multivalent cationic form. Preferably, either theammonium or hydrogen form is employed. They can also be used in intimatecombination with hydrogenating components such as tungsten, vanadium,copper, molybdenum, rhenium, nickel, cobalt, chromium, manganese, or anoble metal such as platinum or palladium where ahydrogenation-dehydrogenation function is to be performed. Suchcomponent can be exchanged into the composition, impregnated therein orphysically intimately admixed therewith. Such component can beimpregnated in or on to the present catalyst such as, for example, inthe case of platinum, by treating the crystalline composition with aplatinum metal-containing ion. Thus, suitable platinum compounds includechloroplatinic acid, platinous chloride and various compounds containingthe platinum amine complexes.

A particularly desirable ionic form is obtained when a metal from theLanthanide series is employed. Lanthanum is preferred because of itsdemonstrated effectiveness. As shown hereinbelow, the USI-10Bcomposition ion exchanged with lanthanum and Redox Treated provides amarked selectivity to C4- aliphatics (93 wt. %) as compared to C5+aliphatics (7 wt. %) and no aromatics when dimethyl ether is passed overthe composition under reaction conditions. A hydrogen ion form, however,for example, produces about 50% C4- and 50% C5+ under similarconditions.

The catalyst, when employed either as an adsorbent or as a catalyst inone of the aforementioned processes, may be heat treated as describedhereinabove.

Members of the present family of crystalline compositions can have theoriginal cations associated therewith replaced by a wide variety ofother cations according to techniques well-known in the art. Typicalreplacing cations would include hydrogen, ammonium and metal cationsincluding mixtures of the same. Of the replacing metallic cations,particular preference is given to cations of metals such as rare earthmetals, manganese and calcium as well as metals of Group II of thePeriodic Table, e.g., zinc and Group VIII of the Periodic Table, e.g.,nickel.

Typical ion exchange techniques include contacting the members of thefamily of borosilicates with a salt solution of the desired replacingcation or cations. Although a wide variety of salts can be employed,particular preference is given to chlorides, nitrates and sulfates.

Representative ion exchange techniques are disclosed in a wide varietyof patents including U.S. Pat. Nos. 3,140,249, 3,140,251 and 3,140,253,which are incorporated herein by reference.

Following contact with the salt solution of the desired replacingcation, the crystalline compositions are then preferably washed withwater and dried at a temperature ranging from 65° C. to about 315° C.and thereafter heat treated as previously described.

Regardless of the cations replacing the sodium in the synthesized formof the catalyst, the spatial arrangement of the atoms which form thebasic crystal lattices in any given composition of this invention remainessentially unchanged by the described replacement of sodium or otheralkali metal as determined by taking an X-ray powder diffraction patternof the ion-exchanged material. For example, the X-ray diffractionpattern of several ion-exchanged compositions reveal a patternsubstantially the same as that set forth in Table 1.

The compositions prepared by the instant invention are formed in a widevariety of particular sizes. Generally speaking, the particles can be inthe form of a powder, a granule, or a molded product, such as extrudatehaving a particle size sufficient to pass through a 2 mesh (Tyler)screen and be retained on a 100 mesh (Tyler) screen. In cases where thecatalyst is molded, such as by extrusion, the composition can beextruded before drying or dried or partially dried and then extruded.

In the case of many catalysts, it is desired to incorporate thecomposition of this invention with another material resistant to thetemperatures and other conditions employed in organic conversionprocesses. Such materials include active and inactive materials andsynthetic or naturally occurring crystalline compositions as well asinorganic materials such as clays, silica and/or metal oxides. Thelatter may be either naturally occurring or in the form of gelatinousprecipitates or gels including mixtures of silica and metal oxides. Useof a material in conjunction with the present catalyst tends to improvethe conversion and/or selectivity of the catalyst in certain organicconversion processes. Inactive materials suitably serve as diluents tocontrol the amount of conversion in a given process so that products canbe obtained economically and in orderly manner without employing othermeans for controlling the rate of reaction. Normally, zeolite materialshave been incorporated into naturally occurring clays, e.g., bentoniteand kaolin, to improve the crush strength of the catalyst undercommercial operating conditions. These materials, i.e., clays, oxides,etc. function as binders for the catalyst. It is desirable to provide acatalyst having good crush strength, because in a chemical process thecatalyst is often subjected to handling or use which tends to break thecatalyst down into powder-like materials which cause problems inprocessing. These clay binders have been employed for the purpose ofimproving the crush strength of the catalyst.

In addition to the foregoing materials, the catalyst can be compositedwith a porous matrix material such as silica-alumina, silica-magnesia,silica-zirconia, silica-thoria, silica-beryllia, silica-titania as wellas ternary compositions such as silica-alumina-thoria,silica-alumina-zirconia, silica-alumina-magnesia andsilica-magnesia-zirconia. The matrix can be in the form of a cogel.

It is an important feature of the invention that the activated catalystbe further activated (Redox Treatment) to provide a composition havingdifferent and/or enhanced catalytic properties, especially for theselective conversion of hydrocarbons or oxygenated compounds to certainuseful products. It has been found that an activated catalyst containingpreferably a hydrogen cation may be so activated by treating theactivated catalyst with a reducing agent for about 1 to 80 hours atabout 200° to 900° C. A preferred treatment is about 2 to 48 hours atabout 400° to 600° C. Any reducing agent may be used or a compound whichunder the treatment conditions forms a reducing agent, such asdimethylether. Dimethylether and hydrogen are preferred because of theirdemonstrated effectiveness. Following the reduction stage, thecomposition is then heat treated, e.g., heated at about 200°-900° C.,preferably 400° to 600° C. for about 1 to 60 hours.

The following examples are presented as specific embodments of thepresent invention and show some of the unique characteristics of theclaimed crystalline compositions and are not to be considered asconstituting a limitation on the present invention.

EXAMPLE 1

This example shows the necessity for preparing a USI-10B compositionusing the method of the invention and the enhanced hydrocarbonconversion thereof when activated using the activation procedure (RedoxTreatment) of the invention and compares it with crystallineborosilicates prepared using a different method.

PREPARATION OF SAMPLE A

16 grams (g) of Cab-O-Sil, Grade MS-7, 6.3 g NaOH and 1.7 gethylenediaminetetraacetic acid (EDTA) were mixed in boiling water. Asecond aqueous mixture was prepared containing 1.01 g boric acid and37.6 g tetrapropylammonium bromide (TPA-Br) in water at roomtemperature. While still hot, the second mixture was added to the firstmixture. The total weight is about 300 g. The combined mixture wasplaced in a teflon container and heated in a sealed autoclave maintainedat about 185° C. for 31/2 days. After cooling, the mixture was filteredusing a small amount of Jaguar C-13 (Celanese) as a filtering andsettling aid, and the recovered crystalline material was washed withcopious quantities of deionized water and dried at 120° C. for about 10hours in an air oven. The yield was approximately 16.2 g and the driedmaterial was identified by X-ray diffraction as a crystalline materialhaving the typical USI-10B pattern shown in Table 1.

About 11.5 g of the dried borosilicate was heated in air at about 538°C. for 16 hours. After cooling, it was refluxed with a solution of 27 gNH₄ Cl in 110 ml. (milliliters) water for 41/2 hours. The mixture wasthen filtered and the borosilicate washed with copious quantities ofdeionized water. The ion exchange was repeated using a solution of 20 gNH₄ Cl in 105 ml. water and refluxed for 18 hours. The ammoniumexchanged material was collected and washed on a filter with copiousquantities of deionized water using a small amount of Jaguar C-13 anddried at 120° C.-125° C. for 20 hours. To test the material foractivity, 5 g of the dried material was loaded into a quartz reactor(1.5 centimeters (cm)×25 cm) and heated to about 500° C. under flowingair for about 20 hours. The air was then discontinued and the specifiedreactant, to wit, dimethyl ether (DME) fed into the reactor at a weighthourly space velocity (WHSV) of about 1.5. The pressure was essentiallyatmospheric with about a 4-6 pounds per square inch gauge (psig)backpressure.

PREPARATION OF SAMPLE 1

Sample 1 was prepared using essentially the same procedure as for SampleA except that no EDTA was used and the digestion period in the autoclavewas about 9 days at 165° C.

PREPARATION OF SAMPLES 2 AND 3

Samples 2 and 3 were prepared using essentially the same procedure asfor Sample A except that Ludox AS-40 (DuPont) was used as the silicasource and no EDTA was used for Sample 2. Sample 2 was digested forabout 7 days at 168° C. and Sample 3 for about 10 days at 166° C.

Samples A and 1-3 after drying all had similar X-ray diffractionpatterns as shown in Table 1. The following data are summarizedhereinbelow in Table 2.

                  TABLE 2                                                         ______________________________________                                                      SAMPLE NO.                                                                    A     1       2       3                                         ______________________________________                                        EDTA            Yes     No      No    Yes                                     Al (wppm)*      67      67      306   434                                     SiO.sub.2 /Al.sub.2 O.sub.3 (molar)*                                                          13,200  13,200  2,890 2,031                                   SiO.sub.2 /B.sub.2 O.sub.3 (molar)*                                                           155     169     141   117                                     DME                                                                           % Conversion    37 (83) 0 (0)   100   100                                     Product Dist. (wt. %)                                                         CH.sub.3 OH     10 (9)  --      2     0                                       H.sub.2 O       28 (37) --      37    33                                      Hydrocarbon     62 (54) --      61    66                                      Wt. % Hydrocarbon                                                             Selectivity                                                                   C.sub.4 - Aliphatics                                                                          53 (50) --      32    28                                      C.sub.5 + Aliphatics                                                                          47 (49) --      57    64                                      Aromatics       0 (1)   --      11    8                                       ______________________________________                                         () = Values obtained after "Redox Treatment" of heating with DME at about     500° C., for 2-3 hours, followed by heating in air at 500°      C. for at least 18 hours.                                                     *Calculated on dried catalyst before ion exchange.                       

The results shown in Table 2 clearly demonstrate the invention. Thus, acomparison of Sample A and Sample 1 shows that at low levels ofaluminum, EDTA is needed in the reaction mixture since, without EDTA, noconversion of DME is obtained and the conversion is not increased byemploying the Redox Treatment noted herein.

Samples 2 and 3 show the high reactivity for the conversion of DME torelatively high levels of aromatics, usually associated with a highaluminum content. Similarly, Sample 3 reacted with ethylene at a 64%conversion at 420° C. to produce a mixture of 40% C₄ - aliphatics, 57%C₅ + aliphatics and 3% aromatics whereas Sample A after Redox Treatmentdid not react with ethylene.

EXAMPLE 2

This example demonstrates the preparation of a USI-10B material using areflux digestion procedure at two different levels of chelating agentand activation thereof by the "Redox Treatment".

PREPARATION OF SAMPLE B

74.3 g. silica (Cab-O-Sil, Grade M-5), 25.9 g. NaOH and 0.701 g. EDTAwere dissolved in boiling water and cooled to 25° C. Total solutionvolume was 800 ml. A second solution (total volume of 400 ml) wasprepared by dissolving 34.7 g TPA-Br, 8.7 g boric acid, 87.1 g NaCl and22.3 g concentrated H₂ SO₄ in water and cooling to 25° C. The secondsolution was slowly added to the silica solution with stirring. Duringthe addition, the solution formed a gel which broke up as more solutionand additional water (about 200 ml) were added. After the addition wascomplete, the mixture was rapidly mixed for about 1 hour in a 2000 mlpolypropylene flask. The pH was about 8.9. A condenser was attached tothe flask and was placed in an oil bath at 111° C. for 63/4 days. Afterremoving from the oil bath and cooling the pH was about 10.6. The samplewas washed with copious quantities of deionized water, collected on afilter and dried at 120° C. for about 45 hours. The sample weight was71.7 g. The sample was then heated and ion exchanged as described inExample 1. After ion exchange, the sample was heated in air at about500° C. for 18 hours. After cooling, 5 g of the material was loaded intoa quartz reactor (1.5 cm×25 cm) and DME passed through the reactor at atemperature of about 420° C. and a WHSV of about 1.5.

PREPARATION OF SAMPLE C

The same procedure as for Sample B was used except that 80 g silica,27.7 g NaOH, 8.8 g EDTA, 33.6 g TPA-Br, 8.9 g boric acid, 85.3 g N_(a)Cl and 19 g H₂ SO₄ was used. The volume of the silica solution was about900 ml and the TPA-Br solution about 500 ml. The initial pH was 8.5, thefinal pH about 10.4 and the digestion period was 111/2 days.

The following data are summarized hereinbelow in Table 3.

                  TABLE 3                                                         ______________________________________                                                          Sample No.                                                                    B     B*    C       C*                                      ______________________________________                                        Al (wppm)**         33            33                                          SiO.sub.2 /Al.sub.2 O.sub.3 (molar)**                                                             23,500        23,500                                      SiO.sub.2 /B.sub.2 O.sub.3 (molar)**                                                              54            60                                          DME                                                                           % Conversion        20      54    42    71                                    Product Dist. (Wt. %)                                                         CH.sub.3 OH         63      33    7     8                                     H.sub.2 O           9       16    31    37                                    Hydrocarbon         28      51    62    55                                    Wt. % Hydrocarbon Selectivity                                                 C.sub.4 - aliphatics                                                                              95      40    49    59                                    C.sub.5 + aliphatics                                                                              5       56    51    40                                    Aromatic            0       4     0     1                                     ______________________________________                                         *Redox Treated by heating with DME at about 500° C. for about 3        hours, followed by heating in air at 500° C. for at least 18 hrs.      **Calculated on dried catalyst before ion exchange.                      

EXAMPLE 3 Organic Adsorption Properties

The organic adsorption properties of USI-10B were compared with aborosilicate material, both before and after Redox Treatment, by adding0.5 g of each adsorbent and 5 ml of the aqueous organic solution (1% byvolume for methanol, n-butanol and methyl cellosolve and 0.1% forphenol) to glass vials stoppered with rubber, teflon coated serum caps.Vials containing only the aqueous organic solution served as a blank.All the vials were attached to a motor driven wheel, agitated for 2hours and equilibrated for at least 10 hours before analysis. Theresults were statistically analyzed.

PREPARATION OF SAMPLE D AND D*

This sample is the same as Sample C, supra, and is the form after ionexchange and heating in air as described therein. Sample D* was preparedby heating Sample D in a quartz tube in air to 500° C., purging withnitrogen and then Redox Treating by heating with hydrogen for 21 hoursat 500° C., cooling and followed by heatng in air for 16 hours at about538° C.

PREPARATION OF SAMPLE 4 AND 4*

Sample 4 was prepared using the procedure described to prepare Sample 1with the following amounts being employed: 16 g of Cab-O-Sil and 12.5 g(50% NaOH solution) were dissolved in 100 ml water by boiling. 1.01 gboric acid, 37.6 g TPA-Br were dissolved in 100 ml water at roomtemperature. The solutions were combined and heated in a sealedautoclave for 91/2 days at 170° C. The yield after drying for about 18hours at 110° C. was about 12 g.

About 10 g of the dried borosilicate was heated in air at about 532° C.for 16 hours, ion exchanged at reflux for 4 hours with a solution of17.4 g NH₄ Cl in 100 ml H₂ O, washed, ion exchanged for 16 hours withfresh NH₄ Cl solution, washed, filtered and dried. 8.2 g of the driedmaterial was heated in air for 16 hours at about 500° C.

Sample 4* was prepared by treating Sample 4 as described for Sample D*above.

                  TABLE 4                                                         ______________________________________                                                        Sample No.                                                                    D and D*  4 and 4*                                            ______________________________________                                        Al (wppm)**       33          13                                              SiO.sub.2 /Al.sub.2 O.sub.3 (molar)**                                                           23,500      60,000                                          SiO.sub.2 /B.sub.2 O.sub.3 (molar)**                                                            60          155                                             ______________________________________                                         **Calculated on dried catalyst before ion exchange.                      

                  TABLE 5                                                         ______________________________________                                        % ORGANIC REMOVED                                                                                        Methyl                                             Sample  Methanol  n-Butanol                                                                              Cellosolve                                                                              Phenol                                   ______________________________________                                        D       25.2 ± 1.5                                                                           98.7 ± 0.4                                                                           68.2 ± 0.5                                                                          95.8 ± 0.5                            D*      20.9 ± 0.9                                                                           95.3 ± 0.5                                                                           74.5 ± 0.7                                                                          91.7 ± 0.5                            4       13.8 ± 1.8                                                                           98.8 ± 0.2                                                                           71.6 ± 0.9                                                                          95.7 ± 0.6                            4*      16.3 ± 1.4                                                                           99.1 ± 0.1                                                                           71.7 ± 0.5                                                                          95.8 ± 0.3                            ______________________________________                                    

The data in Table 5 clearly show the different adsorption propertiesbetween the borosilicates of the invention (D and D*) versusborosilicates not of the invention (4 and 4*). Further, the effect ofthe Redox Treatment significantly alters the adsorption properties ofthe borosilicates of the invention D and D* while not statisticallyaltering the borosilicates 4 and 4*.

EXAMPLE 4 Nitrogen Isotherm Properties

The nitrogen isotherm properties of Samples 4 and 4* of Example 3 and Eand E* were obtained using a Micromeritics 2100D Orr Surface-Area PoreVolume Analyzer. E and E*, of the invention, were prepared using amethod similar to that for Sample C of Example 2 except that the RedoxTreatment is the same as described in Example 3. E and E* contain 22wppm aluminum, have a SiO₂ /Al₂ O₃ molar ratio of 35,000 and a SiO₂ /B₂O₃ molar ratio of 55. The sample size was approximately 0.1 g and allsamples were degassed at 260° C. for 2 hours under a vacuum of 10⁻⁴ mm(millimeters) Hg. The isotherms were determined at liquid nitrogentemperatures using the method shown in the Journal of American ChemicalSociety, Brunaner, S. and Emmett, P. H., Vol. 59 (1937), page 310, saidarticle being incorporated herein by reference. Measurements were madefrom an equilibrium pressure of about 0.002 mm Hg to saturation pressureand equilibrium was established if the equilibrium pressure remainedconstant for at least 30 seconds. Isotherm data were calculated usingthe equation shown in the Journal of Applied Chemical Society, Brunaner,S., Emmett, P. H. and Teller, E. Vol. 60 (1938), page 309 and Vol. 62(1940), page 1723, both articles being incorporated herein by reference.The results are shown in FIGS. 1-4 and show that significant differencesexist between the materials prepared by the method of the inventionusing EDTA (FIG. 1, Sample E and FIG. 2, Sample E*) versus materials notprepared according to the invention (FIG. 3, Sample 4 and FIG. 4, Sample4*).

EXAMPLE 5

This example demonstrates the need for employing a chelating agent inthe digestion reaction mixture.

Crystalline borosilicates (USI-10B) prepared in a similar manner to theprocedure described in Example 1 were comparatively tested after RedoxTreatment for conversion of DME at 420° C. and 1.5 WHSV. Sample 5 wasprepared without EDTA in the reaction mixture and Sample 6 was preparedby extracting Sample 5 (which was in the NH₄ ⁺ form) with EDTA in anamount essentially equivalent to that employed to prepare Sample E,which was prepared by employing EDTA in the reaction mixture. Theresults are as follows:

                  TABLE 6                                                         ______________________________________                                                     SAMPLE                                                                        E*      5         6                                              ______________________________________                                        % Conversion   97        0          2                                         Product Dist.                                                                 CH.sub.3 OH    20        --        --                                         H.sub.2 O      26        --        --                                         Hydrocarbon    54        --        --                                         Hydrocarbon                                                                   Distribution (Wt. %)                                                          C.sub.4 -      41        --        29                                         C.sub.5 +      56        --        71                                         Aromatics       3        --         0                                         ______________________________________                                    

EXAMPLE 6

This example demonstrates the use of a USI-10B material which was ionexchanged with lanthanum and Redox Treated.

About 5.6 g of the USI-10B material prepared in Example 2, Sample No. C(and in the NH₄ ⁺ ion form) was ion exchanged with 9.8 g LaCl₃.6H₂ O in50 ml. water by refluxing for 21/2 hours. The exchanged material waswashed by decantation three times using deionized water, collected on afilter and dried for 20 minutes at 130° C. in an air oven. 5.4 g wasrecovered and 5.0 g charged into a reactor 1.5 cm×25 cm and heated inflowing air at 500° C. overnight. DME at 1.5 WHSV and 420° C. was thenpassed through the reactor and 7% was converted to methanol. After RedoxTreatment using DME at 500° C. for 2 hours, followed by heating in airat 500° C. for 18 hours, DME was again passed through the reactor at420° C. and a 20% conversion resulted with, by weight %, 43% CH₃ OH, 14%H₂ O and 43% hydrocarbons being formed. The selectivity to hydrocarbonsshowed 93% C₄ - aliphatics, 7% C₅ + aliphatics and no aromatics.

It will be apparent that many changes and modifications of the severalfeatures described herein may be made without departing from the spiritand scope of the invention. It is therefore apparent that the foregoingdescription is by way of illustration of the invention rather thanlimitation of the invention.

What is claimed is:
 1. A method of preparing a crystalline metalsilicate which is substantially free of aluminum having a composition,in terms of mole ratios as follows:0.8±0.4 M₂ /_(n) O:W₂ O₃ :5 to 500SiO₂ :0 to 100 H₂ O where M is a cation, n is the valence of said cationand W₂ O₃ is a metal oxide, said metal silicate having the X-raydiffraction pattern set forth in Table 1 of the specification, and anitrogen isotherm adsorption capacity as shown in FIG. 1 which comprisespreparing a reaction mixture which is substantially free of aluminumions and which contains tetraalkylammonium compound, sodium hydroxide,an oxide of the desired metal, an oxide of silicon, water and analuminum chelating agent effective to provide a catalytically activecrystalline metal silicate, maintaining the mixture at an elevatedtemperature until crystals of said metal silicate are formed andseparating and recovering said crystals, and in terms of mole ratiosfalling within the following ranges, the reaction mixture contains:

    ______________________________________                                        OH.sup.- /Si O.sub.2                                                                            .05-3                                                       R.sub.4 N.sup.+ /(R.sub.4 N.sup.+ + Na.sup.+)                                                   0.1--H.sub.2 O/OH 10-500                                    SiO.sub.2 /W.sub.2 O.sub.3                                                                      5-500                                                       SiO.sub.2 /Chelating agent                                                                      1-1000                                                      ______________________________________                                    

wherein R is propyl.
 2. A method as in claim 1 wherein the metal isboron and the aluminum content is an amount of less than about 100 wppmbased on the weight of silica in the reaction mixture.
 3. A method as inclaim 2 wherein the chelating agent is selected from the groupconsisting of ethylene diamine tetraacetic acid, nitrilioriacetic acidand 8-hydroxyquinoline.
 4. A method as in claim 3 wherein the chelatingagent is ethylene diamine tetraacetic acid.
 5. A method of activating acrystalline metal silicate which is substantially free of aluminumhaving a composition, in terms of mole ratios as follows:0.8±0.4 M₂/nO:W₂ O₃ :5 to 500 SiO₂ :O to 100 H₂ O where M is a cation, n is thevalence of said cation and W₂ O₃ is a metal oxide, said metal silicatehaving the X-ray diffraction pattern set forth in Table 1 of thespecification, and a nitrogen isotherm adsorption capacity as shown inFIG. 1 which comprises: (1) Heat treating the dried silicate compositionat about 200° to 900° C. (2) Treating the heated silicate with areducing agent for about 1 to 80 hours at about 200° to 900° C.; and (3)Heat treating the reduced silicate following the procedure of step (1).6. A method as in claim 5 wherein the silicate heat treated in step (1)is in the hydrogen ion form.